2003 Chevrolet Astro Owner's Manual - Page 144

Defogging and Defrosting Turn the right knob to select the defog or defrost mode. Rear Heating System Your vehicle may have an optional rear heating system that allows you to adjust the amount of air flowing into the rear of the vehicle, from the front-seating area. This feature works with the main climate-control system in your vehicle. +3(Blend): With this setting, the outside air comes out of both the floor and defroster outlets. Adjust the temperature knob for warmer or cooler air. The air conditioning compressor may operate in this setting to dehumidfy the air. 9(Defrost): This setting operates the defroster. Most of the air comes out near the windshield, with some going to the floor outlets and front side windows. The air conditioning compressor may operate in this setting to dehumidify the air. The bi-level setting is useful for cold weather with a large number of passengers or very humid conditions to help keep the windshield clear. Use defrost to remove fog or ice from the windshield quickly in extremely cold conditions. The temperature knob should be in the red area and the fan control toward high. The thumbwheel for this system is located to the right of the audio system. Turn the thumbwheel up or down to increase or decrease the amount of heated air sent to the rear-seating area. 3-19